Surgery must be performed using clean and sterile instruments in order to prevent infection. Other medical devices also require cleaning and/or sterilization to maintain sanitary conditions in hospitals and other medical settings.
Surgical instruments must be cleaned and sterilized before every procedure, and each operation leaves biological residue on the instruments from the patient's body. This residue must be completely removed prior to sterilization. Some of these biological residues can be resilient and difficult to remove from the instruments. Thus, cleaning surgical instruments after a procedure requires specialized equipment and techniques.
The problem of bodily residue removal is further compounded by opportunistic organisms such as bacteria and fungi from the ambient environment and/or patient that colonize the instruments. These organisms produce a crude extra-cellular matrix in order to protect the cells in their colonies. This matrix is referred to as biofilm and usually comprises a disorganized web of long polymer strands interspersed with live cells and proteins. Biofilm is a highly effective anchoring and protection for bacterial and fungal colonies—as a result it is notoriously difficult to clean. Once a medical instrument is coated in biofilm, it is very difficult to fully clean and sterilize.
Currently several devices and solvents are used to clean instruments and remove biofilm. Although these systems are somewhat effective, they are not 100% effective and may require vigorous scrubbing and/or repeated cleaning. For example, surgical technicians usually use an inexpensive polyurethane foam material to wipe instruments. This foam will typically be soaked in detergent. Although the foam effectively delivers the detergent to the biofilm (resulting in a chemical degradation of the biofilm), the foam is not effective at mechanically abrading and removing the biofilm. This is because most common abrasive materials (including foam) do not have a microscopic structure capable of abrading biofilm.
Removing biofilm and biological residue from the exterior of medical instruments is challenging, but these difficulties are exacerbated in the context of endoscope or catheter lumen cleaning. Performing surgery using endoscopes is preferable to conventional open surgery because of lower patient mortality and morbidity. Endoscopy produces these more favorable outcomes because fewer unnecessary incisions are made to the patient in order to access the target tissue. However, cleaning and sterilizing endoscopes is difficult and necessary because endoscopes are expensive and must be reused to be economical.
During endoscopic surgery, the endoscope is inserted into the patient and oftentimes will have at least one lumen that evacuates fluids from the patient. This is done in order to remove unwanted materials such as resected tissue, cauterized tissue, blood, cellular contents, extra-cellular fluid, plasma, lymph, etc. . . . from the patient's body during the operation. This is done in order to improve visibility for the endoscopic camera and/or to reduce irritation/inflammation of surrounding tissues and reduce unwanted accumulation of fluid.
Once the endoscopic surgery is completed, not only is the endoscope's exterior coated with biological residue, but the interior of the lumens are as well. This residue must be completely removed from the endoscope before it can be reused for another procedure, since complete sterility is needed for any surgical instrument. Furthermore, the lumen interior is highly susceptible to hosting invasive organisms and accumulating biofilm.
The state of the art for cleaning and removing biofilm from lumen interiors is also essentially limited to detergent delivery systems (i.e. suctioning detergent through the lumen) and basic scrubbing devices. Many lumen cleaners use a “push through” design whereby a short scrubber is pushed through the lumen. A short scrubber must be used to prevent buckling as the scrubber moves through the channel. The Caterpillar™ endoscopic channel brush by Cygnus Medical, LLC is a pull-through design using a relatively rigid leader that is threaded through the channel. The leader is then used to pull a relatively long brush through the channel for improved cleaning. Although the Caterpillar™ represents a significant improvement, it employs a conventional scrubber brush and its ability to remove biofilm could be improved. Removing biofilm within lumens is a particularly demanding task, since the lumen interior is not physically accessible for vigorous scrubbing. Therefore, it is desirable to use the most abrasive material possible for cleaning the interiors of lumens.
One currently available highly abrasive material is melamine foam. Melamine foam only needs water to effectively remove most residues—no detergents or surfactants are required. Melamine foam has a unique microscopic structure that allows it to be both flexible and highly abrasive. When melamine resin cures into foam, its microstructure becomes very hard (almost as hard as glass), causing it to act like a very fine sandpaper. Melamine foam is flexible despite the base material's hardness because it is an open-celled foam, meaning that it is a sparse network of very hard strands. The open-cellular structure also aids in its cleaning ability because dirt particles are pulled into open cells and removed from the surface being cleaned. Despite these desirable qualities, melamine foam is not suitable for sterile cleaning applications because it crumbles as it scrubs. Leaving foam and debris particles on the instruments being cleaned is completely unacceptable for sterile applications as it virtually assures infection and contamination.
There remains a need in the art for a medical instrument cleaner that can simultaneously deliver detergent to biofilm while mechanically abrading, dislodging, and removing biofilm from the instrument without crumbling. It is particularly important to provide a device capable of fully removing biofilm from the interior of a catheter or endoscope lumen.